Abietinaria abietina (Linnaeus, 1758) (additional source)
Abludomelita obtusata (Montagu, 1813) (additional source)
Acanthochondria cornuta (Müller O.F., 1776) (additional source)
Acanthodasys aculeatus Remane, 1927 (additional source)
Acanthomysis longicornis (Milne Edwards, 1837) (additional source)
Acartia clausi Giesbrecht, 1889 accepted as Acartia clausii Giesbrecht, 1892 (additional source)
Acartia discaudata (Giesbrecht, 1882) represented as Acartia (Acartiura) discaudata (Giesbrecht, 1881) (additional source)
Acasta spongites (Poli, 1791) (additional source)
Achaeus cranchii Leach, 1817 (additional source)
Achelia echinata Hodge, 1864 (additional source)
Achelia hispida Hodge, 1864 (additional source)
Achnanthes longipes C.Agardh, 1824 (additional source)
Acipenser sturio Linnaeus, 1758 (additional source)
Acrochaetium daviesii (Dillwyn) Nägeli, 1862 accepted as Colaconema daviesii (Dillwyn) Stegenga, 1985 (additional source)
Acrorhynchides caledonicus (Claperede, 1861) Strand, 1928 (additional source)
Actinia equina (Linnaeus, 1758) (additional source)
Actinia fragacea Tugwell, 1856 (additional source)
Actinocyclus octonarius Ehrenberg, 1837 accepted as Actinoptychus octonarius (Ehrenberg) Kützing, 1844 accepted as Actinocyclus octonarius var. octonarius Ehrenberg, 1837 (additional source)
Actinocyclus subtilis (W.Gregory) Ralfs, 1861 (additional source)
Actinoptychus senarius (Ehrenberg) Ehrenberg, 1843 accepted as Actinocyclus senarius Ehrenberg, 1838 (additional source)
Actinoptychus splendens (Shadbolt) Ralfs ex Pritchard, 1861 (additional source)
Actinothoe sphyrodeta (Gosse, 1858) (additional source)
Actitis hypoleucos (Linnaeus, 1758) (additional source)
Adamsia carciniopados (Otto, 1823) accepted as Adamsia palliata (Fabricius, 1779) accepted as Calliactis palliata (Müller, 1776) (additional source)
Adamsia palliata (Bohadsch, 1761) accepted as Adamsia palliata (Fabricius, 1779) accepted as Calliactis palliata (Müller, 1776) (additional source)
Adenorhynchus balticus Meixner, 1938 (additional source)
Aepophilus bonnairei Signoret, 1879 (additional source)
Aepopsis robinii (Laboulbene, 1849) (additional source)
Aequorea forskalea Péron & Lesueur, 1810 (additional source)
Aequorea vitrina Gosse, 1853 (additional source)
Aetea anguina (Linnaeus, 1758) (additional source)
Agaue chevreuxi (Trouessart, 1889) (additional source)
Aglaophamus rubella (Michaelsen, 1897) accepted as Aglaophamus agilis (Langerhans, 1880) (additional source)
Aglaophenia pluma (Linnaeus, 1758) (additional source)
Aglaothamnion hookeri (Dillwyn) Maggs & Hommersand, 1993 accepted as Gaillona hookeri (Dillwyn) Athanasiadis, 2016 (additional source)
Aglaothamnion roseum (Roth) Maggs & L'Hardy-Halos, 1993 accepted as Gaillona rosea (Roth) Athanasiadis, 2016 (additional source)
Aglaothamnion scopulorum (C.Agardh) Feldmann-Mazoyer, 1941 (additional source)
Agonus cataphractus (Linnaeus, 1758) (additional source)
Ahnfeltia plicata (Hudson) E.M.Fries, 1836 (additional source)
Alca torda Linnaeus, 1758 (additional source)
Alcyonidium albidum Alder, 1857 (additional source)
Alcyonidium condylocinereum Porter, 2004 (additional source)
Alcyonidium diaphanum (Hudson, 1778) (additional source)
Alcyonidium gelatinosum (Linnaeus, 1761) (additional source)
Alcyonidium hirsutum (Fleming, 1828) (additional source)
Alcyonidium mytili Dalyell, 1848 accepted as Alcyonidioides mytili (Dalyell, 1848) (additional source)
Alcyonidium parasiticum (Fleming, 1828) (additional source)
Alcyonium digitatum Linnaeus, 1758 (additional source)
Alentia gelatinosa (M. Sars, 1835) (additional source)
Aleochara (Emplenota) obscurella Gravenhorst, 1806 (additional source)
Aleochara (Polystomota) grisea (Kraatz, 1806) (additional source)
Alle alle (Linnaeus, 1758) (additional source)
Allogromia ovoidea Rhumbler, 1904 (additional source)
Alopias vulpinus (Bonnaterre, 1788) (additional source)
Alosa alosa (Linnaeus, 1758) (additional source)
Alosa fallax (Lacepède, 1803) (additional source)
Alpheus glaber (Olivi, 1792) (additional source)
Alpheus macrocheles (Hailstone, 1835) (additional source)
Alteutha depressa (Baird, 1837) (additional source)
Alteutha interrupta (Goodsir, 1845) (additional source)
Alteutha oblonga (Goodsir, 1845) (additional source)
Amaeana trilobata (Sars, 1863) (additional source)
Amathia lendigera (Linnaeus, 1758) (additional source)
Amblyosyllis formosa (Claparède, 1863) accepted as Amblyosyllis spectabilis (Johnston in Baird, 1861) (additional source)
Ameira brevipes Kunz, 1954 accepted as Filexilia brevipes (Kunz, 1954) (additional source)
Ameira hyalina (Noodt, 1952) accepted as Psammameira hyalina Noodt, 1952 (additional source)
Ameira parvula (Claus, 1866) (additional source)
Ammodytes tobianus Linnaeus, 1758 (additional source)
Ammothella longipes (Hodge, 1864) (additional source)
Ammotrypane aulogaster Rathke, 1843 accepted as Ophelina acuminata Örsted, 1843 (additional source)
Ampelisca brevicornis (A. Costa, 1853) (additional source)
Ampelisca diadema (A. Costa, 1853) (additional source)
Ampelisca spinipes Boeck, 1861 (additional source)
Ampelisca spooneri Dauvin & Bellan-Santini, 1982 accepted as Ampelisca pectenata Reid, 1951 (additional source)
Ampelisca tenuicornis Liljeborg, 1856 (additional source)
Ampelisca typica (Spence Bate, 1857) (additional source)
Ampharete baltica Eliason, 1955 (additional source)
Amphiascoides debilis (Giesbrecht, 1881) (additional source)
Amphiascus minutus (Claus, 1863) accepted as Sarsamphiascus minutus (Claus, 1863) (additional source)
Amphiascus parvus Sars G.O., 1906 accepted as Mesamphiascus parvus (Sars G.O., 1906) accepted as Sarsamphiascus parvus (Sars G.O, 1906) (additional source)
Amphiascus varians (Norman & Scott T., 1905) accepted as Mesamphiascus varians (Norman & Scott T., 1905) accepted as Sarsamphiascus varians (Norman & Scott T., 1905) (additional source)
Amphiblestrum flemingii (Busk, 1854) (additional source)
Amphilochus manudens Spence Bate & Westwood, 1862 (additional source)
Amphilochus neapolitanus Della Valle, 1893 accepted as Apolochus neapolitanus (Della Valle, 1893) (additional source)
Amphinema dinema (Péron & Lesueur, 1810) (additional source)
Amphipholis squamata (Delle Chiaje, 1828) (additional source)
Amphiporus bioculatus sensu Verrill, 1892 (additional source)
Amphiporus lactifloreus (Johnston, 1828) (additional source)
Amphirhynchus caudatus Schilke, 1970 (additional source)
Amphisbetia operculata (Linnaeus, 1758) (additional source)
Amphitrite cirrata Müller, 1776 (additional source)
Amphitritides gracilis (Grube, 1860) (additional source)
Amphiura (Acrocnida) brachiata (Montagu, 1804) accepted as Acrocnida brachiata (Montagu, 1804) (additional source)
Amphiura filiformis (O.F. Müller, 1776) (additional source)
Amphiura securigera (Düben & Koren, 1846) represented as Amphiura (Ophiopeltis) securigera (Düben & Koren, 1846) (basis of record)
Amphora commutata Grunow, 1880 (additional source)
Amphora ocellata Donkin, 1861 (additional source)
Amphora ovalis (Kützing) Kützing, 1844 (additional source)
Ampithoe helleri Karaman, 1975 accepted as Pleonexes helleri (Karaman, 1975) (additional source)
Ampithoe rubricata (Montagu, 1808) (additional source)

Belgian Exclusive Economic Zone for Paratomella rubra Rieger & Ott, 1971 
Wimereux for Akera bullata O. F. Müller, 1776  (doubtful)
Wimereux for Aplysia punctata (Cuvier, 1803)  (doubtful)
Wimereux for Crepidula fornicata (Linnaeus, 1758)  (origin: alien)
Wimereux for Philine punctata (J. Adams, 1800) 

Dutch baksteenanemoontje for Diadumene cincta Stephenson, 1925
Dutch bruine korstanemoon for Epizoanthus couchii (Johnston in Couch, 1844)
Dutch dodemansduim for Alcyonium digitatum Linnaeus, 1758
Dutch draadroos for Anemonia viridis (Forsskål, 1775)
Dutch edelsteenroos for Bunodactis verrucosa (Pennant, 1777)
Dutch gekromde zeeborstel for Hydrallmania falcata (Linnaeus, 1758)
Dutch golfbrekeranemoontje for Diadumene cincta Stephenson, 1925
Dutch grauwe cilinderroos [from synonym] for Cerianthus lloydii Gosse, 1859
Dutch groene golfbrekeranemoon [from synonym] for Diadumene luciae (Verrill, 1869)
Dutch haringgraat for Halecium halecinum (Linnaeus, 1758)
Dutch heremietzeeanemoon for Calliactis parasitica (Couch, 1842)
Dutch kleine klokpoliep for Clytia gracilis (M. Sars, 1851)
Dutch knikkende zeeanjelier for Cereus pedunculatus (Pennant, 1777)
Dutch kogelkwal for Pleurobrachia pileus (O. F. Müller, 1776)
Dutch mantelanemoon [from synonym] for Adamsia carciniopados (Otto, 1823)
Dutch margrietje for Actinothoe sphyrodeta (Gosse, 1858)
Dutch meloenkwalletje for Beroe gracilis Künne, 1939
Dutch mijterkwal for Beroe gracilis Künne, 1939
Dutch paardenanemoon for Actinia equina (Linnaeus, 1758)
Dutch rimpelige tandhorenkoraal for Sertularella rugosa (Linnaeus, 1758)
Dutch rode paardenanemoon for Actinia equina (Linnaeus, 1758)
Dutch sierlijke slibanemoon [from synonym] for Sagartia elegans (Dalyell, 1848)
Dutch slanke mijterkwal for Beroe gracilis Künne, 1939
Dutch symbiontische zeeanemoon [from synonym] for Adamsia carciniopados (Otto, 1823)
Dutch tapijtschelp for Venerupis geographica (Gmelin, 1791)
Dutch vertakte zeespriet for Nemertesia ramosa (Lamarck, 1816)
Dutch viltkokeranemoon [from synonym] for Cerianthus lloydii Gosse, 1859
Dutch wasroos for Anemonia viridis (Forsskål, 1775)
Dutch weduweroos [from synonym] for Sagartiogeton undatus (Müller, 1778)
Dutch weduweroosje for Actinothoe sphyrodeta (Gosse, 1858)
Dutch witte platworm for Oligocladus sanguinolentus Lang, 1884
Dutch wrattige zeeanemoon for Bunodactis verrucosa (Pennant, 1777)
Dutch zeebaard for Nemertesia antennina (Linnaeus, 1758)
Dutch zeecypres for Sertularia cupressina Linnaeus, 1758
Dutch zeedahlia for Urticina felina (Linnaeus, 1761)
Dutch zeedruif for Beroe gracilis Künne, 1939
Dutch zeedruifje for Pleurobrachia pileus (O. F. Müller, 1776)
Dutch zeemadeliefje [from synonym] for Sagartia elegans (Dalyell, 1848)
Dutch zeepluim for Aglaophenia pluma (Linnaeus, 1758)
Dutch zeespriet for Nemertesia antennina (Linnaeus, 1758)
Dutch zeetamarinde for Amphisbetia operculata (Linnaeus, 1758)
Dutch zonneroos for Cereus pedunculatus (Pennant, 1777)
French actinie commensale [from synonym] for Adamsia carciniopados (Otto, 1823)
French actinie rouge for Actinia equina (Linnaeus, 1758)
French aeufde méduse for Pleurobrachia pileus (O. F. Müller, 1776)
French aigrette garzette for Egretta garzetta (Linnaeus, 1766)
French albatros à sourcils noirs [from synonym] for Diomedea melanophris Temminck, 1828
French alcyon commum for Alcyonium digitatum Linnaeus, 1758
French alcyon jaune for Alcyonium digitatum Linnaeus, 1758
French algue a gouttiere for Pelvetia canaliculata (Linnaeus) Decaisne & Thuret, 1845
French algue feutrée dichotome for Codium tomentosum Stackhouse, 1797
French alouette haussecol for Eremophila alpestris (Linnaeus, 1758)
French amande de mer for Glycymeris glycymeris (Linnaeus, 1758)
French amille for Ammodytes tobianus Linnaeus, 1758
French amphioxus for Branchiostoma lanceolatum (Pallas, 1774)
French anatife [from synonym] for Lepas anatifera Linnaeus, 1758
French anémone dahlia for Urticina felina (Linnaeus, 1761)
French anémone de mer verte for Anemonia viridis (Forsskål, 1775)
French anémone encroûtante brune for Epizoanthus couchii (Johnston in Couch, 1844)
French anémone flammeé for Diadumene cincta Stephenson, 1925
French anémone palmée for Cereus pedunculatus (Pennant, 1777)
French anémone plumeuse for Metridium senile (Linnaeus, 1761)
French anémone solitaire for Calliactis parasitica (Couch, 1842)
French anséropode for Anseropoda placenta (Pennant, 1777)
French antiopelle [from synonym] for Janolus cristatus (Delle Chiaje, 1841)
French aphrodite [from synonym] for Aphrodite aculeata (Linnaeus, 1758)
French aplysie ponctuée for Aplysia punctata (Cuvier, 1803)
French araignée de mer for Achaeus cranchii Leach, 1817
French arénicole for Arenicola marina (Linnaeus, 1758)
French ascidie à siphons écartes for Ascidia mentula Müller, 1776
French ascidie jaune for Ciona intestinalis (Linnaeus, 1767)
French ascidie massue orange for Polyclinum aurantium Milne Edwards, 1841
French ascidie plissée for Styela clava Herdman, 1881
French ascidie rectangulaire for Ascidia virginea Müller, 1776
French ascidie rose for Ascidia mentula Müller, 1776
French ascidie rugueuse for Ascidiella scabra (Müller, 1776)
French ascidie sale for Ascidiella aspersa (Müller, 1776)
French aspidophore for Agonus cataphractus (Linnaeus, 1758)
French astérie for Asterias rubens Linnaeus, 1758
French athérine [from synonym] for Atherina (Hepsetia) presbyter Cuvier, 1829
French auxide for Auxis thazard (Lacepède, 1800)
French avocette élégante for Recurvirostra avosetta Linnaeus, 1758
French balane commune [from synonym] for Balanus perforatus Bruguière, 1789
French balane de nouvelle [from synonym] for Elminius modestus Darwin, 1854
French balbuzard pêcheur for Pandion haliaetus (Linnaeus, 1758)
French baleine à bec de Cuvier for Ziphius cavirostris Cuvier, 1823
French baliste for Balistes capriscus Gmelin, 1789
French barge à queue noire for Limosa limosa (Linnaeus, 1758)
French barge rousse [from synonym] for Limosa laponica (Linnaeus, 1758)
French barge rousse for Limosa lapponica (Linnaeus, 1758)
French baudrier de Neptune [from synonym] for Laminaria saccharina (Linnaeus) J.V.Lamouroux, 1813
French baudroie for Lophius piscatorius Linnaeus, 1758
French bec de jar for Mya arenaria Linnaeus, 1758
French bécasseau cocorli for Calidris ferruginea (Pontoppidan, 1763)
French bécasseau de Baird for Calidris bairdii (Coues, 1861)
French bécasseau de Bonaparte for Calidris fuscicollis (Vieillot, 1819)
French bécasseau de tacheté for Calidris melanotos (Vieillot, 1819)
French bécasseau falcinelle for Limicola falcinellus (Pontoppidan, 1763)
French bécasseau maubèche for Calidris canutus (Linnaeus, 1758)
French bécasseau minute for Calidris minuta (Leisler, 1812)

 Authority

 for Unciola crenatipalma (Spence Bate, 1863)

(Bate, 1855) [details]

 Spelling

 for Chaetoceros curvisetus Cleve, 1889

Referred to as Chaetoceros curvisetum by some sources. [details]

 Spelling

 for Chaetoceros danicus Cleve, 1889

Referred to as Chaetoceros danicum by some sources. [details]

 Spelling

 for Chaetoceros debilis Cleve, 1894 emend Xu, Y.Li & Lundholm in Xu et al., 2020

Referred to as Chaetoceros debile by some sources. [details]

 Spelling

 for Chaetoceros densus (Cleve) Cleve, 1899

Referred to as densum by some sources. [details]

 Spelling

 for Chaetoceros didymus Ehrenberg, 1845

Referred to as Chaetoceros didymum by N. I. Hendey. [details]

 Spelling

 for Chaetoceros socialis H.S.Lauder, 1864

Also referred to as Chaetoceros sociale. [details]

 Spelling

 for Chaetoceros wighamii Brightwell, 1856

Also referred to as Chaetoceros wighami. [details]